Hydrostatic press for an elongated object



June 4, 1963 c. GERARD ETAL 3,091,804

HYDROSTATIC PRESS FOR AN ELONGATED OBJECT Filed May 24, 1961 INVENTORS. G GE G R RD 8:

/ BY JA B BR AN fheir ATTORNEYS June 1963 G. GERARD ETAL HYDROSTATIC PRESS FOR AN ELONGATED OBJECT 2 Sheets-Sheet 2 Filed May 24, 1961 FIG 2 5 v) w M NDN M ERA Av M r W EN M A United Stes are This invention relates to hydrostatic presses of the multi-anvil type and, more particularly, to a new and improved hydrostatic press especially adapted to apply extreme pressure to .an elongated object. This application is a continuation-in-part of our copending application Serial No. 45,608, filed July 27, 1960, for Multi-Anvil Apparatus and Test Bodies Therefor, and now Patent 3,080,609, granted March 12, 1963.

As described in our above-mentioned copending application, extreme pressures can be applied to an object or workpiece by surrounding the workpiece with a plurality of wedge-shaped pressure-multiplying anvil members within a pressure-resistant housing and applying conventional high pressure uniformly to the outer surfaces of all the anvil members. Moreover, as pointed out in the above-mentioned application, the principle of that invention is particularly useful in applying extreme pressures to an elongated workpiece. This is because the problems encountered with conventional piston and cylinder pressure apparatus, i.e., Wall friction between the workpiece and the cylinder and elastic enlargement and tensile loading of the cylinder in response to increased internal pressure, are effectively eliminated.

In one embodiment of the invention described in our above-mentioned application, an apparatus for applying extreme pressures to an elongated object, referred to as a delta apparatus, is described which comprises three separable, angularly disposed assemblies, each including an anvil member radially slidable in a channel of limited width. Pressure is applied to each anvil member by a plurality of pistons exposed to a supply of hydraulic fluid under pressure.

Because of the limited channel width resulting from the configuration of the delta apparatus, the outer areas of the anvil members to which pressure is applied is restricted to a relatively small fraction of the maximum peripheral area of the apparatus. Furthermore, the delta apparatus has a relatively complex structure and includes sliding piston and cylinder arrangements which necessitate accurate fabrication and assembly of the components.

Accordingly, it is an object of the present invention to provide a new and improved hydrostatic press for compressing an elongated object which overcomes the abovementioned disadvantages of presently known presses.

Another object of the invention is to provide a new and improved hydrostatic press for an elongated object which has a simple and compact structure and is convenient to operate.

These and other objects of the invention are accomplished by providing an elongated pressure-multiplying structure having an outer surface portion and end surface portions and consisting of a plurality of wedge-shaped anvil members. Each anvil member has an outer surface forming a part of the outer surface portion, end surfaces each forming a part of one of the end surface portions, and an inner surface forming, in conjunction with the inner surfaces of the other anvil members, an elongated object-receiving cavity. In order to supply conventional high pressure uniformly to the outer surfaces of the wedgeshaped anvil members, the outer surface portion of the pressure-multiplying structure is surrounded by a housing arranged to receive fluid under pressure and sealing means is provided between the housing and the anvil members to prevent the fluid from escaping between the pressuremultiplying structure and the housing. Preferably, the sealing means comprises a resilient sleeve of rubber or the like surrounding the pressure-multiplying structure and aflixed at opposite ends to the housing to provide an annular fluid-receiving chamber.

If desired, each anvil assembly may comprise two or more portions made of different materials to accommo date the increasing pressure within the anvil toward the center of the pressure-multiplying structure, and, in addition, strips of resilient supporting material may be located along the junctions of adjacent anvil members adjacent to the resilient sleeve to prevent the sleeve from extruding into the gaps between the anvils when it is under pressure. Positioning devices for adjusting the position of the anvil assemblies with respect to each other may be mounted on the adjacent surfaces of the anvil members and, in order to provide access to these devices, longitudinally extending recesses may be made in the adjacent anvil surfaces.

Further objects and advantages of the invention will be apparent from a reading of the following description in conjunction with the accompanying drawings, in which:

FIG. 1 is a view in vertical section through a typical hydrostatic press arranged according to the invention, taken on line l1 of FIG. 2; and

FIG. 2 is a cross-sectional view of the press shown in FIG. 1, taken on the line 22 thereof and looking in the direction of the arrows.

As illustrated in the drawings, a representative embodiment of the invention comprises a cylindrical shell 10 having two end portions 11 and 12 projecting inwardly toward the axis of the cylinder to form internal shoulders 13 and 14, respectively. In order to facilitate assembly of the apparatus, the end portion 11 is .a separate member attached to the shell 10 by threads. Both the portions 11 and 12 are formed with access openings 11' and 12', respectively, to permit access to the interior of the shell. Within the shell 10 is a cylindrical pressure-multiplying structure 15 which, as best seen in FIG. 2, consists of three wedge-shaped anvil assemblies 16, 1'7, and 18, and surrounding the periphery of this structure is a flexible sleeve 19 made of rubber or the like, which is sealingly attached at opposite ends to the shoulders 13 and 14 by clamp rings 20 and 21, respectively. Consequently, a sealed annular chamber 22 is formed about the structure 15 and a fluid inlet duct 23 leading into this chamber is provided in the lower shoulder portion 12 of the outer shell.

The anvil members are in the form of segments of a cylinder divided longitudinally along radial planes and each member has a large area outer surface 16', 17', 18' in contact with the sleeve 19 and a small area inner surface 16", 17", 18", the latter surfaces forming an axially extending cavity to receive a workpiece assembly 24. Although the illustrated embodiment of the invention utilizes three anvil members to form an internal workpiece-receiving cavity of triangular cross-section, it will be understood that any number of anvil members may be utilized and that the workpiece-receiving cavity may have any desired shape in accordance with the cross-sectional shape of the intended workpiece, provided the multiplica tion factor (ratio of effective outer surface area to effective inner surface area) is the same for all the anvil members. For example, the internal cavity may have a square, hexahedral or octahedral cross-section, requiring four, six, or eight anvil members, respectively, or it may be a polygon with sides of unequal length and corresponding anvils of unequal size may be provided. In addition, the inner surfaces forming the cavity need not be planar but instead some or all of them may be curvilinear so that a workpiece having an irregular cross-sectional shape can be compressed. In addition, there may be variations in the cross-sectional size of the cavity throughout its length to accommodate an elongated workpiece having a longitudinal irregular shape.

Inasmuch as the pressure near the inner surfaces of the anvil members is substantially greater than that near the outer surfaces, each anvil member may comprise a plurality of rigidly joined anvil portions made of different materials, the inner portion being harder than the outer portions. For example, the anvil 16 consists of an outer portion 16a, a central portion .161), and an inner portion 160, the portion 16c being made of tungsten carbide orthe like. At the junction between the periphery of the pressure-multiplying structure and the interface between each adjacent pair of anvil members a triangular strip 25 of resilient supporting material, such as rubber, is inserted in a mating groove formed by bevelliug the two members so as to prevent the sleeve 19 from being forced into the gap between the anvils when pressure is applied to the chamber 22.

As pointed out inour above-mentioned copending application, when the length of an elongated workpiece is more than a few times its maximum thickness and pressure is to be applied only in directions substantially perpendicular to the longitudinal axis of the workpiece, it is not necessary to support the workpiece in the axial direction with the same pressure that is applied to its sides. Accordingly, in the apparatus of the present invention, as shown in FIG. 1, two end blocks 26 and 27 are positioned at opposite ends of the pressure-multiplying structure 15, and are removably joined together by three tie rods 28 extending longitudinal through corresponding holes 29 in each of the anvil members 16, 17, and 18. These rods hold the end blocks together with only enough pressure to contain the workpiece assembly 24 and the blocks do not press against the end surfaces of the pressure-multiplying structure with suflicient force to prevent relative movement of the anvil members in the radial direction, the holes 29 being larger than the diameter of the rods 28 so as to permit such relative motion. Alternatively, if desired, the end blocks 26 and 27 may be connected to the end portions 11 and 12, respectively, of the shell 10.

Before pressure is applied, the workpiece assembly 24 is larger than the cavity formed by the surfaces 16", 17", and .18" by an amount commensurate with the intended degree of compression of the workpiece and with the amount needed to provide material for the sealing gas vents. Consequently, in order to insert the workpiece assembly in the cavity, the anvil members must be forced apart against the friction of their contact with the ends of the shell and the resilience of the flexible sleeve 19. To accomplish this, a plurality of anvil adjusting devices 30 is provided between each pair of anvils along their adjacent surfaces and, to permit access to these from the ends of the apparatus, the adjacent surfaces are recessed to form an elongated cavity 34.

In the illustrated embodiment of the invention, as best seen in FIG. 2, each adjusting device 30 comprises a cylinder 32 having a pair of opposed pistons 33 and 34 connected through piston rods 35 and 36 to the adjacent anvil members respectively, a recess 37 being cut into each anvil surface to receive the cylinder. Preferably, the piston rods "35 and '36 are pivotally attached to the anvil members to permit some freedom of angular motion of the anvils with respect to each other. The pistons are actuated to force the anvils apart by applying pneurnatic or hydraulic pressure through a line 38 which leads to the portion of the cylinder 32 between the two pistons; 'If desired, the piston and cylinder arrangements may be replaced by compression springs and appropriate mechanical linkages which are capable of forcing the anvil members apart when no pressure is applied to the chamber 22, but can readily be overcome by the application of pressure to the outer surfaces of the three anvil assemblies.

The workpiece assembly 24 which, before compression, holds the anvil assemblies apart so as to produce small gaps 39 between the anvils, consists of an object to be compressed embedded in a material which is normally rigid but becomes viscous under high pressures. By reason of this property pressure is transmitted from the anvils uniformly throughout the workpiece and the workpiece containing material is extruded slightly into the gaps 39 so that it forms a seal and prevents further extrusion of the material into the gaps. Preferably, the workpiece containing material is aluminum silicate or a pyrophyllite such as Tennessee Grade A Lava which provides the necessary electrical and heat insulation characteristics. 'In addition, the workpiece assembly 24 may include the usual electrical heating elements (not shown), which are described in detail in our above-identified copending application, to raise the temperature of the workpiece to a desired value while pressure is applied.

In operation, a workpiece assembly 24 is inserted in the apparatus by removing the end blocks 26 and 27 to expose the internal cavity and applying hydraulic or pneumatic pressure to the lines 38 to spread the anvil members apart. After the workpiece assembly has been placed in the cavity the pressure in the line 38 is released, permitting the anvils to engage the sides of the workpiece assembly in the manner shown in FIG. 2, leaving gaps 39 between the adjacent anvil surfaces because of the oversize of the workpiece assembly. The end blocks 26 and 27 are then replaced and conventional high pressure is applied to the chamber 22 by passing a fluid such as oil or water through the conduit 23, the workpiece being heated to an elevated temperature, if desired. This pressure, acting through the sleeve 19, drives the anvil members inwardly to compress the workpiece, applying a pressure thereto which is equal to the pressure in the chamber 22 multiplied by the ratio of the outer surface areas of the anvil members 16, 17, and 18 to their inner surface areas. After compression, the end blocks are removed and the anvils are spread apart by operation of the devices 30 so that the workpiece assembly can be withdrawn from the cavity.

It will be readily apparent from the foregoing that the present invention provides a press for applying extreme pressures to elongated objects which is simple and compact in structure while at the same time being convenient in operation and overcoming the shortcomings of conventional high pressure apparatus.

Although the invention has been described herein with reference to a specific embodiment, many modifications and variations therein will readily occur to those skilled in the art. Accordingly, all such variations and modifications are included within the intended scope of the invention as defined by the following claims.

We claim:

1. Apparatus for applying extreme pressure to an elongated object comprising a housing, a plurality of wedgeshaped pressure-multiplying anvil members within the housing forming an elongated pressure-multiplying structure having an outer surface portion and two end surface portions, each anvil member having a large area outer surface forming a part of the outer surface portion of the structure, two end surfaces each forming a part of the end surface portions of the structure, and a small area inner surface forming, in conjunction with the corresponding inner surfaces of the other anvil members, an elongated central object receiving cavity, resilient pressure-transmitting means surrounding the outer surface portion of the pressure multiplying structure, means forming a seal between the resilient pressure-transmitting means and the housing to form an annular pressure-tight chamber surrounding the pressure-multiplying structure,

means for introducing fluid under high pressure into thev annular chamber, and a strip of resilient material located at the junction of the outer surfaces of each pair of adjacent anvil members to prevent extrusion of the pressure-transmitting means between the anvil members.

2. Apparatus for applying extreme pressure to an elongated object comprising a housing, a plurality of wedgeshaped pressure-multiplying anvil members within the housing forming an elongated pressure-multiplying structure having an outer surface portion and two end surface portions, each anvil member having a large area outer surface forming a part of the outer surface portion of the structure, two end surfaces each forming a part of the end surface portions of the structure, and a small area inner surface forming, in conjunction with the corresponding inner surfaces of the other anvil members, an elongated central object receiving cavity, resilient pressure-transmitting means surrounding the outer surface portion of the pressure multiplying structure, means forming a seal between the resilient pressure-transmitting means and the housing to form an annular pressure-tight chamber surrounding the pressure-multiplying structure, means for introducing fluid under high pressure into the annular chamber, means disposed at opposite ends of the central cavity for confining an object within the cavity, and means for confining an object within the cavity comprises a pair of blocking members abutting the opposite end surface portions of the structure respectively, and means extending through the anvil members joining the pair of blocking members.

3. Apparatus for applying extreme pressure to an elongated object comprising a housing, a plurality of wedgeshaped pressure-multiplying anvil members within the housing forming an elongated pressure-multiplying structure having an outer surface portion and two end surface. portions, each anvil member having a large area outer surface forming a part of the outer surface portion of the structure, two end surfaces each forming a part of the end surface portions of the structure, and a small area inner surface forming, in conjunction with the corresponding inner surfaces of the other anvil members, an elongated central object receiving cavity, resilient pressure-transmitting means surrounding the outer surface portion of the pressure multiplying structure, means forming a seal between the resilient pressure-transmitting means and the housing to form an annular pressure-tight chamber surrounding the pressure-multiplying structure, means for introducing fluid under high pressure into the annular chamber, and anvil positioning means connecting each pair of adjacent anvil members along their adjacent surfaces effective to urge to enlarge the central cavity.

4. Apparatus according to claim 3 wherein the anvil positioning means comprises piston and cylinder means including a pair of members each connected to one of the adjacent anvil members and means for supplying fluid pressure to the piston and cylinder means to urge the anvil members apart.

5. Apparatus according to claim 3 including recess means in the adjacent surfaces of each adjacent pair of anvil members forming an elongated cavity to provide access to the positioning means.

6. Apparatus for applying extreme pressure to an elongated object comprising a housing, a plurality of wedgeshaped pressure-multiplying anvil members within the housing forming an elongated pressure-multiplying structure having an outer surface portion and two end surface portions, each anvil member having a large area outer.

surface forming a part of the outer surface portion of the structure, two end surfaces each forming a part of the. end surface portions of the structure, and a small area inner surface forming, in conjunction with the corresponding inner surfaces of the other anvil members, an elongated central object receiving cavity, resilient pressure-transmitting means surrounding the outer surface the anvil members apart portion of the pressure multiplying structure, means forming a seal between the resilient pressure-transmitting means and the housing to form an annular pressure-tight chamber surrounding the pressure-multiplying structure, means for introducing fluid under high pressure into the annular chamber, and wherein the resilient pressuretransmitting means comprises a sleeve surrounding the pressure-multiplying structure and the means forming a seal comprises clamping means for clamping the sleeve at opposite ends to the housing.

7. In apparatus for applying extreme pressure to an object, a plurality of wedge-shaped pressure-multiplying anvil members each having a small area inner surface, a large area outer surface, and a side surface adjacent to the side surface of an adjacent anvil member, forming a pressure-multiplying structure to transmit pressure applied to the outer surfaces of the members to an object located within the region bounded by the inner surfaces, and anvil positioning means connecting each pair of adjacent anvil members along their adjacent surfaces effective to urge the anvil members apart.

8. In apparatus for applying extreme pressure to an elongated object, a plurality of relatively movable wedgeshaped pressure-multiplying anvil members forming an elongated pressure-multiplying structure having an outer,

surface portion and two end surface portions and a cen tral object-receiving cavity extending therethrough, and means for confining the object within the cavity comprising a pair of blocking members abutting the opposite end surface of the structure and means extending through the anvil members and joining the blocking members.

9. In apparatus for applying extreme pressure to an object, a plurality of wedge-shaped pressure-multiplying anvil members each having a small area inner surface, a large area outer surface, and a side surface adjacent to the side surface of an adjacent anvil member, forming a pressure-multiplying structure to transmit pressure applied to the outer surfaces of the members to an object located within the region bounded by the inner surfaces, resilient pressure-transmitting means surrounding the structure to apply pressure to the outer surfaces of the members and supporting means disposed along the junctions of the outer surfaces of the anvil members adjacent to the resilient pressure-transmitting means to prevent the press lre-transmitting means from being forced between the anvil members.

10. Apparatus for applying extreme pressure to an elongated object comprising a tubular housing having inwardly projecting shoulder portions at each end, a plurality of wedge-shaped pressure-multiplying anvil members within the housing forming an elongated generally cylindrical pressure-multiplying structure having an outer surface portion adjacent to the inner wall of the housing and two end surface portions adjacent to the inwardly projecting shoulder portions, each anvil member having a large area outer surface forming a part of the outer surface portion of the pressure-multiplying structure, two end surfaces each forming a part of the end surface portions of the structure, and a small area inner surface forming, in conjunction with the corresponding inner surfaces of the other anvil members, an elongated central object-receiving cavity, a pair of block members abutting the opposite end surface portions of the structure to confine an object within the cavity, means extending through the anvil members joining the blocking members, a sleeve of resilient pressure-transmitting material surrounding the outer surface portion of the structure, clamping means for aflixing the ends of the sleeve to the housing shoulder portions to form an annular pressure-tight chamber surrounding the structure, and means for introducing fluid under high pressure into the chamber.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Coolidge May 15, 1917 Wright May 9, 1922 5 Dows Feb. 11, 1930 Kraft Feb. 18, 1936 8 Cobi Aug. 22, 1939 Whipple Aug. 19, 1941 McCall Apr. 6, 1943 Kennison Jan. 17, 1956 Billner Jan. 3, 1961 Gerard et al. July 17, 1962 

1. APPARATUS FOR APPLYING EXTREME PRESSURE TO AN ELONGATED OBJECT COMPRISING A HOUSING, A PLURALITY OF WEDGESHAPED PRESSURE-MULTIPLYING ANVIL MEMBERS WITHIN THE HOUSING FORMING AN ELONGATED PRESSURE-MULTIPLYING STRUCTURE HAVING AN OUTER SURFACE PORTION AND TWO END SURFACE PORTIONS, EACH ANVIL MEMBER HAVING A LARGE AREA OUTER SURFACE FORMING A PART OF THE OUTER SURFACE PORTION OF THE STRUCTURE, TWO END SURFACES EACH FORMING A PART OF THE END SURFACE PORTIONS OF THE STRUCTURE, AND A SMALL AREA INNER SURFACE FORMING, IN CONJUNCTION WITH THE CORRESPONDING INNER SURFACES OF THE OTHER ANVIL MEMBER, AN ELONGATED CENTRAL OBJECT RECEIVING CAVITY, RESILIENT PRESSURE-TRANSMITTING MEANS SURROUNDING THE OUTER SURFACE PORTION OF THE PRESSURE MULTIPLYING STRUCTURE, MEANS FORM- 